method

merge

v3.0.7 - Show latest stable - 1 note - Class: ActiveRecord::SpawnMethods

1.0.0
1.1.0
1.1.1
1.1.6
1.2.0
1.2.6
2.0.0
2.0.1
2.0.3
2.1.0
2.2.1
2.3.2
2.3.8
3.0.0 (0)
3.0.5 (0)
3.0.7 (0)
3.0.9 (0)
3.1.0 (0)
3.2.1 (0)
3.2.3 (0)
3.2.8 (0)
3.2.13 (0)
What's this?

merge(r) public

No documentation

This method has no description. You can help the Ruby on Rails community by adding new notes.

# File activerecord/lib/active_record/relation/spawn_methods.rb, line 5
    def merge(r)
      merged_relation = clone
      return merged_relation unless r
      return to_a & r if r.is_a?(Array)

      Relation::ASSOCIATION_METHODS.each do |method|
        value = r.send("#{method}_values""#{method}_values")

        unless value.empty?
          if method == :includes
            merged_relation = merged_relation.includes(value)
          else
            merged_relation.send("#{method}_values=""#{method}_values=", value)
          end
        end
      end

      (Relation::MULTI_VALUE_METHODS - [:joins, :where, :order]).each do |method|
        value = r.send("#{method}_values""#{method}_values")
        merged_relation.send("#{method}_values=""#{method}_values=", merged_relation.send("#{method}_values""#{method}_values") + value) if value.present?
      end

      order_value = r.order_values
      if order_value.present?
        if r.reorder_flag
          merged_relation.order_values = order_value
        else
          merged_relation.order_values = merged_relation.order_values + order_value
        end
      end

      merged_relation = merged_relation.joins(r.joins_values)

      merged_wheres = @where_values + r.where_values

      unless @where_values.empty?
        # Remove duplicates, last one wins.
        seen = Hash.new { |h,table| h[table] = {} }
        merged_wheres = merged_wheres.reverse.reject { |w|
          nuke = false
          if w.respond_to?(:operator) && w.operator == :==
            name              = w.left.name
            table             = w.left.relation.name
            nuke              = seen[table][name]
            seen[table][name] = true
          end
          nuke
        }.reverse
      end

      merged_relation.where_values = merged_wheres

      Relation::SINGLE_VALUE_METHODS.reject {|m| m == :lock}.each do |method|
        value = r.send("#{method}_value""#{method}_value")
        merged_relation.send("#{method}_value=""#{method}_value=", value) unless value.nil?
      end

      merged_relation.lock_value = r.lock_value unless merged_relation.lock_value

      # Apply scope extension modules
      merged_relation.send :apply_modules, r.extensions

      merged_relation
    end

March 27, 2012

2 thanks

Makes it possible to use a scope through an association

This is a very useful method if you want to to use a scope through an association:

class Book < ActiveRecord::Base
  scope :available, where(:available => true)
end

class Author < ActiveRecord::Base
  has_many :books
  scope :with_available_books, joins(:books).merge(Book.available)
end

# Return all authors with at least one available book:
Author.with_available_books

See http://asciicasts.com/episodes/215-advanced-queries-in-rails-3 for more info.

merge

Related methods

No documentation

Makes it possible to use a scope through an association

Flowdock - Team Inbox With Chat